I made this summery video of much of the info gleaned from this great forum along with some video of the pump. I hope it helps others, it took a lot of reading to dig up all the relevant info.



I'll also add, this pump was supposed to have been rebuilt and there is a clear 'dot' of some kind of slightly gritty dark grease inside even after I dumped the oil out. I'm guessing this is either molybdenum disulphide grease or graphite or similar intended to help seal any wear on the pistons. Interesting it was never mixed with the oil though! The pump only got a few cranks because it didn't work Maybe if it did a few hundred miles the two parts would have mixed. Still, seemed excessively gritty to me.



EDIT: Wow I just realised. There is a magnet behind that dot! On the back side of the pump there is a hole and if you put a screwdriver or whatever in there you can clearly feel it's a magnet. This is a catch for magnetic debris, like a magnetic sump plug on a cars oil pan! Wow what a lot of crap there was!!